We are studying the factors which determine the development and function of the retina and pigment epithelium in relation to retinitis pigmentosa and other degenerative diseases. We have now identified a specific receptor for Vitamin A in the retina and pigment epithelium of several species which appears to be different from the retinol-binding protein (RBP) of serum. Study of the role of the Vitamin A receptor in the metabolism of the retina and pigment epithelium may shed light on the normal and abnormal functioning in these tissues.